The present invention relates generally to door interlocks for electrical appliances and in particular for washing machines, tumble driers and dishwashers. Specifically, the present invention relates to a door interlock with an integrated restart lockout for an electrical appliance, which, after opening of a door of the electrical appliance, prevents operation of the latter from being continued by closing the door again.
For safety reasons it is necessary to prevent the operation of electrical appliances (e.g. domestic appliances, in particular washing machines, tumble driers, dishwashers etc.) from being independently, automatically resumed when the door of an appliance actually in operation is opened and then closed again. For said purpose, so-called restart lockouts are used, which ensure that an electrical appliance may not be operated again until a user, after closing the appliance door again, resets the electrical appliance to the operating state by means of a further measure, e.g. by pressing a start button.
In a known restart lockout a switch disposed in the region of the door (door switch) is used, which detects opening of the door. In the case of said electrical solution, the control unit of the electrical appliance is controlled by means of the door switch in a way that prevents restarting when the door is closed again.
A further known restart lockout is actuated likewise by the opening movement of the door. In said case, a mechanical solution is used, in which the door cooperates with a linkage in such a way that opening of a door by means of the linkage brings a master switch (e.g. start button, on/off switch) of an electrical appliance mechanically into a position, which interrupts operation of the electrical appliance. To resume operation, the master switch then has to be actuated once more.
A door interlock for domestic appliances is further known, in which by means of a separate actuating apparatus (Bowden cable) connected to the door interlock a master switch is mechanically brought into a state, which prevents automatic resumption of the operation of the appliance after the door is closed again.
A drawback of the restart lockouts, which are actuated by appliance doors, is that additional actuable components have to be provided in the region of the door and/or of the appliance housing. Furthermore, in the case of the electrical solution, the electrical appliance has to have an electrical control unit or electrically controllable components have to be provided for bringing the master switch mechanically into its non-actuated state. The described use of a linkage, which is actuated by door opening operations, is constructionally complex and tolerance-sensitive.
The use of an actuating apparatus, which cooperates with a door interlock, likewise entails a complex construction of the electrical appliance for connecting the actuating device to the door interlock and guaranteeing actuation of the master switch of the electrical appliance. In particular, the use of a Bowden cable makes said approach susceptible to faults and requires compliance with close tolerances.
Furthermore, in known restart lockouts detection of the open and closed state of the door is not provided.
The object of the present invention is to provide a restart lockout for electrical appliances, which avoids the described drawbacks of known solutions and has small dimensions. A further object of the invention is to enable open and closed positions of a door of an electrical appliance to be determined by means of the restart lockout.
In order to achieve said object, the invention provides a door interlock with a restart lockout for an electrical appliance, in particular for a washing machine, a tumble drier or a dishwasher.
The door interlock according to the invention comprises an interlocking device, which in a closed position interlocks a door of an electrical appliance and in an open position releases the door. The interlocking device may be, for example, a rotary latch closure having a rotary member, which in a closed position is capable of blocking a closing piston by means of a lug and in an open position releases the closing piston, and having a catch, which in a blocking position blocks the rotary member in its closed position and in a release position releases the rotary member for a rotational movement into its open position. For the interlocking device it is also possible to use a closure with longitudinal bolt.
The door interlock according to the invention further comprises a restart lockout device, which in a release state enables operation and in particular restarting of the electrical appliance and in a lockout state interrupts operation of the electrical appliance or prevents restarting. In order, after opening of the door of the electrical appliance, to prevent automatic restarting of the electrical appliance by closing the door again, upon a changeover from the closed position to the open position of the interlocking device the restart lockout device is brought from its release state into its lockout state.
In order to enable (re)starting of the electrical appliance independently of the time, at which the interlocking device changed over into its closed position, the restart lockout device is brought into the release state independently of the changeover of the interlocking device from the open position into its closed position. For said purpose a control signal of the electrical appliance may be used, which is produced e.g. by actuating a master switch or pressing an on/off button, and is operated in such a way that the restart lockout device adopts its release state.
It is further provided that for said purpose an actuator is used, which effects the changeover of the restart lockout device into its release state. Examples of such actuators are electrically controlled actuators (e.g. mechanically acting relays), electromagnetic components (e.g. magnets), piezostrictively operated units and the like.
The change of state of the restart lockout device is preferably effected by means of a mechanical working connection, which exists at least for the period of the change of state, between the interlocking device and the restart lockout device. To said end, the restart lockout device comprises a first actuating member, which in the release state occupies a release position and in the lockout state occupies a lockout position.
For producing an electrical signal, which indicates the activation of the restart lockout, the first actuating member actuates a switch or button, which produces a suitable signal. Depending on the type of switch or button used (e.g. microswitch, micro pushbutton, tumbler switch, slide switch, etc.), the first actuating member cooperates with the switch or button in its release position and/or in its lockout position. A signal thus produced may also be used to indicate whether the door interlock and hence the appliance door is open and/or closed.
The release state for the restart lockout device is preferably achieved by a movement of the first actuating member into the latter""s release position. For said purpose it is possible to use the actuator, which moves the first actuating member from its lockout position into its release position.
In order to determine whether the door of the electrical appliance is open or closed, the door interlock comprises a second actuating member, which in the closed position of the interlocking device occupies a closed position and in the open position of the interlocking device occupies an open position.
When only the first actuating member is used, the interlocking device upon a changeover from its closed position to its open position brings the first actuating member into the latter""s lockout position.
When both actuating members are used, then, starting from the release state, the lockout state of the restart lockout device may be achieved in that the interlocking device upon a changeover from its closed position to its open position cooperates with the second actuating member in such a way that the second actuating member is brought from its closed position into its open position and, in the process, causes a change of position of the first actuating member from the latter""s release position to the latter""s lockout position.
Alternatively, it is provided that the interlocking device upon a changeover from its closed position to its open position brings the first actuating member out of the latter""s release position into the latter""s lockout position, wherein the second actuating member is brought from its closed position into its open position.
In the case of the last-described forms of construction, it is necessary for the first and/or the second actuating member to be of an appropriate design to guarantee the described cooperation. For said purpose it is possible to use e.g. drivers, detents, lugs, etc., which are formed on the first and/or the second actuating member.
In contrast to the first actuating member, the second actuating member takes up its closed position when the interlocking device has changed over into its closed position. Said change of position of the second actuating member is preferably achieved through cooperation with the interlocking device.
To detect the position of the second actuating member a switch or pushbutton may be used, which, in a comparable manner to the switch or pushbutton actuable by the first actuating member, is actuated by the second actuating member in the latter""s closed position and/or the latter""s open position.
If the first actuating member is to be secured in its release position, then a device acting substantially independently of the interlocking device is required. For said purpose it is possible to use e.g. a locating spring, which secures the first actuating member in its release position. The locating spring may also be used to hold the first actuating member in the latter""s lockout position. Alternatively, it is provided that the securing in the lockout position is provided by means of a suitable working connection to the interlocking device.
As the positions of the second actuating member are dependent upon the positions of the interlocking device, it is possible, where desired, to achieve a securing of the second actuating member in its closed position and its open position by means of a corresponding working connection to the interlocking device. To hold the second actuating member in its closed position or in its open position a locating spring may also be used. Preferably, for securing the first actuating member and the second actuating member a common device, e.g. a locating spring, is used.
It is moreover to be preferred that the components of the previously described forms of construction of the door interlock according to the invention are integrated in the form of a constructional unit in a housing.
According to the invention, therefore, the restart lockout is situated in the closure or in the immediate vicinity of the latter and the restart lockout is brought by means of the interlocking element of the closure indirectly or directly into a first stable position as well as by means of an electromagnet into a second stable position. Thus, the invention makes it possible for e.g. a rotary latch closure or a closure with longitudinal bolt to be easily extended by the function of a restart lockout. It is therefore possible in a simple and inexpensive manner to provide a reliable restart lockout also in machines, which have only simple electronic equipment (or even no electronic equipment at all).